1. Field of the Invention
The present invention is directed to a dispensing gun, and more particularly to a hand-held dispensing gun fitted with a cartridge for dispensing a viscous material such as caulking and sealant compounds out of the cartridge.
2. Description of the Prior Art
Dispensing guns for dispensing viscous materials out of a cartridge inserted therein have been extensively used for caulking and sealing operations, one typical example of which is disclosed in U.S. Pat. No. Re. 26,180. The prior dispensing guns generally include a housing with a hand grip, a barrel extending from the housing to receive a cartridge containing a supply of viscous material. The cartridge has its rear end wall formed by a piston which is pushed forwardly by a plunger extending from the housing to force the contents of the cartridge out of a spout at the front end thereof. To practice the caulking and sealing procedures with this cartridge type dispensing gun, it is quite common to firstly cut off the end of the spout at an angle of about 45.degree. and then move the gun along the joint to be treated by squeezing the trigger of the gun for applying a continuous bead of viscous material by making use of the angled edge of the spout as a spatula. With this angled edge of the spout serving as the spatula, the viscous material being dispensed can be readily filled in the joint as well as a smooth finish of the bead can be obtained. However, this procedure utilizing the angled edge of the spout will certainly pose a problem where the operator is required to move the gun around as when changing the advancing direction thereof, for example, in the case of applying caulking or sealing around window and door frames. In such operation situs, the operator is forced to frequently change the manner of holding the gun or rotating the cartridge about its axis when advancing the gun vertically along the sides of the frame and horizontally along the top or bottom of the frame in order to keep the angled edge of the spout in effective contact with the surface to be treated, which compels the operator to proceed with the operation in an uncomfortable posture and sometimes requires the operator to interrupt the operation for reloading the cartridge. To avoid the above problem, it may be thought reasonable to provide the barrel receiving the cartridge freely rotatable about its axis with respect to the housing such that the cartridge can be rotated together with the barrel for adjusting the orientation of the its angled edge of the spout without shifting the grip of the gun. However, there still remains a problem in that the barrel or the cartridge might fluctuate or be rendered unstable when moving the gun around so that the angled edge of the spout would be out of effective contact with the surface to be treated. Therefore, the operator is required to constantly hold the barrel unrotated at a desired position with one hand for effectively utilizing the angled edge of the spout when moving the gun with the other hand, which is inconvenient in producing fatigue of the operator's arms and restricts the use of the gun to a limited operational site where the operator is allowed to use both hands solely for manipulating the gun, practically prohibiting one handed operation of the gun.
Consequently, it is most desirable to present a dispensing gun capable of being manipulated by one hand, yet permitting the operator to utilize the angled edge of the spout of a cartridge as a spatula for effectively applying a smoothly finished bead of the dispensed viscous material.